Rolling element intermediate shaft assembly

ABSTRACT

A rolling element intermediate shaft assembly includes a solid shaft having first and second ends. Also included is a tubular shaft configured to receive the first end, the tubular shaft having an inner wall with an axially extending groove formed therein, the axially extending groove having an inner surface. Further included is a wear plate having a bottom surface and an elastically deformable body having first and second ends, the body defining an axially extending channel, the body of the wear plate received in the tubular shaft groove. Yet further included is an outer surface of the body of the wear plate defining a gap between the wear plate and the axially extending groove of the tubular shaft, the gap reduced upon flexure of the wear plate. Also included is at least one ball bearing disposed within the wear plate channel between the wear plate and the solid shaft.

CROSS-REFERENCES TO RELATED APPLICATIONS

This patent application is a divisional application of U.S. patentapplication Ser. No. 14/283,974, filed May 21, 2014 (now abandoned),which claims priority to U.S. Provisional Patent Application Ser. No.61/825,884 filed May 21, 2013, which is incorporated herein by referencein its entirety.

FIELD OF THE INVENTION

The present disclosure generally relates to shaft couplings and, morespecifically, to intermediate shaft assemblies for vehicles.

BACKGROUND OF THE INVENTION

Intermediate shafts (I-shafts) are designed to be a component of torquetransfer from a steering column to a steering gear. They may also allowaxial movement while maintaining this ability to transfer torque. Someknown I-shafts control the torsional rate and axial sliding forcethrough clearance control and friction, and these I-shafts are commonlyreferred to as friction slider I-shafts.

Some know friction slider I-shafts are composed of a metal solid shaftwith a plastic based coating sliding inside of a metal tube. Many ofthese friction sliders must maintain extremely tight tolerances. As aresult, because cross-sections of these components vary by application,the plastic based coating that is placed over the metal solid shaft mustbe customized to fit the specific tube it will be positioned in. Assuch, this process is difficult to use and maintain on a mass productionscale. Accordingly, it is desirable to provide an I-shaft with variabletolerances such that it may be used with various sized I-shaftcomponents.

SUMMARY OF THE INVENTION

In one aspect, a rolling element intermediate shaft assembly includes asolid shaft having a first end and a second end. Also included is atubular shaft configured to receive the first end of the solid shaft,the tubular shaft having an inner wall with an axially extending grooveformed therein, the axially extending groove having an inner surface.Further included is a wear plate having a bottom surface and anelastically deformable body having a first end and a second end, thebody defining an axially extending channel, the body of the wear platereceived in the tubular shaft axially extending groove. Yet furtherincluded is an outer surface of the body of the wear plate defining agap between the wear plate and the axially extending groove of thetubular shaft, the gap reduced upon flexure of the wear plate. Alsoincluded is at least one ball bearing disposed within the wear platechannel between the wear plate and the solid shaft.

In another aspect, a method of assembling a rolling element intermediateshaft assembly is provided. The method includes providing a solid shafthaving a first end and a second end. Also included is providing atubular shaft having an inner wall with an axially extending grooveformed therein, the axially extending groove having an inner surface.Further included is providing a wear plate having a bottom surface anddefining an axially extending channel. Yet further included is orientingthe wear plate in the tubular shaft axially extending groove with a gapdefined by the wear plate and the tubular shaft axially extendinggroove. Also included is inserting the solid shaft into the tubularshaft. Further included is inserting at least one ball bearing withinthe wear plate channel between the wear plate and the solid shaft.

These and other advantages and features will become more apparent fromthe following description taken in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter which is regarded as the invention is particularlypointed out and distinctly claimed in the claims at the conclusion ofthe specification. The foregoing and other features, and advantages ofthe invention are apparent from the following detailed description takenin conjunction with the accompanying drawings in which:

FIG. 1 is an exploded view of a rolling element I-shaft assembly inaccordance with the invention;

FIG. 2 is a perspective view of an exemplary solid shaft of the I-shaftassembly shown in FIG. 1;

FIG. 3 is a perspective view of an exemplary wear plate of the I-shaftassembly shown in FIG. 1;

FIG. 4 is a perspective view of an exemplary tubular shaft of theI-shaft assembly shown in FIG. 1;

FIG. 5 is a cross-sectional view of a portion of the I-shaft assemblyshown in FIG. 1, after assembly, and taken along line 5-5;

FIG. 6 is a sectional view of the I-shaft assembly shown in FIG. 5, andtaken along line 6-6; and

FIG. 7 is an enlarged view of a portion of the I-shaft assembly shown inFIG. 6, and taken along section 7.

DETAILED DESCRIPTION

Referring now to the Figures, where the invention will be described withreference to specific embodiments, without limiting same, FIG. 1illustrates an exemplary rolling element intermediate shaft (I-shaft)assembly 10 that generally includes a yoke 12, a solid shaft 14, aroller assembly 16, and a tubular shaft 18. Roller assembly 16 includesa cap 20, ball bearings 22, and wear plates 24. In the exemplaryembodiment, I-shaft assembly 10 is configured for use in a vehiclesteering column assembly (not shown). However, shaft assembly 10described herein may be used in any other suitable system.

FIG. 2 illustrates solid shaft 14, which generally includes a solid body26 having a first end 28 and a second end 30. First end 28 is configuredfor insertion into an aperture 32 of yoke 12 (see FIG. 1) to facilitatecoupling therebetween, and second end 30 is configured for insertioninto tubular shaft 18. Solid body 26 includes grooves 34 extendingaxially along the length of solid shaft 14.

FIG. 3 illustrates wear plate 24, which generally includes a body 36having a first end 38 and a second end 40. First end 38 includes arms 42configured to facilitate holding wear plate 24 in position withintubular shaft 18 (e.g., arms 42 hook on tubular shaft 18), and secondend 40 includes a tab 44 configured to facilitate preventing ballbearings 22 from rolling out of grooves 34 if solid shaft 14 is extendedpast wear plates 24. Wear plate body 36 defines an axially extendingtrack or channel 46 that is configured to receive ball bearings 22, asis described herein in more detail. Wear plate first end 38 isconfigured to be inserted into cap 20, and wear plate second end 40 isconfigured to be inserted into tubular shaft 18. Wear plate 24 is of amaterial capable of elastically deforming within tubular shaft grooves54 in response to a transverse force directed from ball bearings 22.

FIG. 4 illustrates tubular shaft 18, which generally includes a tubularbody 48 having an open end 50 and a yoke end 52. Open end 50 isconfigured to receive roller assembly 16 and solid shaft second end 30,and yoke end 52 is configured to couple to the steering column assembly.Tubular body 48 includes an inner wall 53 having axially extendinggrooves 54 formed therein. Grooves 54 are configured to receive wearplates 24 at least partially therein, as is describe herein in moredetail. Tubular body 48 also includes one or more slot 56 configured toretain cap 20 on tubular shaft open end 50. However, cap 20 may becoupled to tubular shaft 18 in any suitable manner.

With reference to FIGS. 5-7, assembly of I-shaft assembly 10 includesproviding yoke 12, solid shaft 14, roller assembly 16, and tubular shaft18. Wear plates 24 are inserted into tubular shaft open end 50 and areeach oriented within one of tubular shaft grooves 54 such that bottomsurfaces 58 of wear plates 24 are facing inner surfaces 60 of grooves 54(see FIGS. 6 and 7). As shown in FIG. 7, wear plate 24 and/or groove 54are formed such that bottom surface 58 is oriented with respect to innersurface 60 at an angle ‘a’ that is transverse to the axially extendinggrooves 54. In the exemplary embodiment, angle ‘a’ is less than or equalto 10°. However, angle ‘a’ may be any suitable angle that enablesI-shaft assembly 10 to function as described herein. The offset betweenthe surfaces 58, 60 due to angle ‘a’ facilitates a flexible or elasticinterface between wear plate 24 and tubular shaft 18, which prevents oreliminates the need for exact matched pairs and tight tolerances betweencomponents 14, 16, 18 of I-shaft assembly 10. As such, the offsetfacilitates translational movement while minimizing fatigue of the wearplate and preventing movement of wear plates 24 when a torque is appliesto assembly 10. Additionally, as described herein, the type of materialused to fabricate wear plate 24, as well as the thickness of thematerial, may be varied to provide a desired elasticity or flexibilityfor wear plate 24.

Solid shaft second end 30 is inserted into tubular shaft open end 50 andoriented such that grooves 34 are substantially aligned with wear plateschannels 46. As illustrated in FIG. 6, grooves 34, wear plates 24, andgrooves 54 are oriented approximately 180° from each other. However,grooves 34, wear plates 24, and grooves 54 may be oriented with respectto each other at any suitable angle that enables assembly 10 to functionas described herein. Further, assembly 10 may include any number of setsof grooves 34, wear plates 24, and grooves 54. For example, assembly 10may include three or four sets of grooves 34, wear plates 24, andgrooves 54.

In the exemplary assembly, ball bearings 22 are subsequently insertedinto the spaces or tracks formed between grooves 34 and channels 46.During insertion of ball bearings 22, wear plates 24 may flex to take upany tolerance of assembly 10 due to the offset orientation of wear platebottom surfaces 58 and tubular shaft groove inner surfaces 60, asdescribed above. Cap 20 is inserted over solid shaft 14 and is coupledto tubular shaft open end 50 (see FIG. 5), which facilitates securingball bearings 22 within wear plate channels 46 and preventing foreignobjects or contaminants from getting into tubular shaft 18 and hinderingthe operation of roller assembly 16. Yoke 12 may then be coupled tosolid shaft first end 28 in any suitable manner (e.g., press-fitting,welding, etc.).

Described herein are systems and methods for a rolling element I-shaftassembly that includes a tubular shaft, a solid shaft, wear plates, andball bearings. Grooves are formed in the solid shaft outer surface andthe tubular shaft inner surface. The wear plates include channels andare oriented within the tubular shaft grooves proximate the solid shaftgrooves to define tracks therebetween to receive the ball bearings. Thisallows translational motion between the shafts as the ball bearingstravel axially down the tracks. The wear plates also allow forvariations along the solid shaft and tubular shaft by providing aflexible interface between the described components due to an offsetangle between the wear plates and the tubular shaft. Accordingly, arobust I-shaft assembly is provided that facilitates translationalmotion, does not require high tolerances, and maintains high torsionalstrength, durability, and stiffness.

While the invention has been described in detail in connection with onlya limited number of embodiments, it should be readily understood thatthe invention is not limited to such disclosed embodiments. Rather, theinvention can be modified to incorporate any number of variations,alterations, substitutions or equivalent arrangements not heretoforedescribed, but which are commensurate with the spirit and scope of theinvention. Additionally, while various embodiments of the invention havebeen described, it is to be understood that aspects of the invention mayinclude only some of the described embodiments. Accordingly, theinvention is not to be seen as limited by the foregoing description.

Having thus described the invention, it is claimed:
 1. A rolling elementintermediate shaft assembly comprising: a solid shaft having a first endand a second end; a tubular shaft configured to receive the first end ofthe solid shaft, the tubular shaft having an inner wall with an axiallyextending groove formed therein, the axially extending groove having aninner surface; a one-piece wear plate having a bottom surface and anelastically deformable body having a first end and a second end, thebody defining an axially extending channel, the body of the wear platereceived in the tubular shaft axially extending groove; an outer surfaceof the body of the wear plate defining a gap between the wear plate andthe axially extending groove of the tubular shaft, the gap reduced uponflexure of the wear plate; and at least one ball bearing disposed withinthe wear plate channel between the wear plate and the solid shaft, andspaced from the tubular shaft by the wear plate.
 2. The assembly ofclaim 1, further comprising: a second axially extending groove formed inthe tubular shaft inner wall; and a second wear plate received in thetubular shaft second axially extending groove, wherein at least one ballbearing is disposed within the second wear plate channel between thesecond wear plate and the solid shaft.
 3. The assembly of claim 2,wherein the axially extending groove and the second axially extendinggroove are oriented approximately 180° apart from each other.
 4. Theassembly of claim 3, wherein the wear plate and the second wear plateare oriented approximately 180° apart from each other.
 5. The assemblyof claim 1, wherein an offset angle is defined between the wear platebottom surface and the tubular shaft groove inner surface.
 6. Theassembly of claim 5, wherein the offset angle that is transverse to theaxially extending groove of about between 0° and 10°.
 7. The assembly ofclaim 1, wherein the solid shaft includes an outer surface having anaxially extending groove formed therein, wherein the at least one ballbearing is disposed within the wear plate channel and the solid shaftaxially extending groove.
 8. The assembly of 7, wherein the solid shaftincludes a second axially extending groove formed therein.
 9. Theassembly of claim 8, wherein the solid shaft axially extending grooveand the solid shaft second axially extending groove are orientedapproximately 180° apart from each other.
 10. The assembly of claim 1,further comprising a retainer cap coupled to the tubular shaft tofacilitate retention of the at least one ball bearing within the tubularshaft.
 11. The assembly of claim 1, further comprising a yoke coupled tothe solid shaft second end, wherein the tubular shaft further includes ayoke end.